Receiver for signal communication system with disturbance rejection circuit

Abstract

A receiver of a signal communication apparatus; the apparatus having a transmitter for transmitting the signals, the receiver for receiving the signals and a galvanically isolated wireless interface interposed between the transmitter and the receiver and having a transmitting antenna and a receiving antenna. The receiver including a disturbance rejection circuit coupled to the receiving antenna and capable of compensating for the parasite currents flowing between the transmitting antenna and the receiving antenna at the potential variations between the input and output of the galvanic isolation interface.

The invention claimed is: 
     
       1. A receiver, comprising:
 a disturbance rejection block configured to receive signals from a receiving antenna of a galvanically isolated wireless interface and to compensate for parasitic currents flowing between a transmitting antenna and the receiving antenna at potential variations between an input and an output of the galvanically isolated wireless interface, wherein the disturbance rejection block includes:
 a common-mode disturbance rejection block configured to take up parasitic currents present on terminals of the receiving antenna; and 
 a common-mode voltage biasing block configured to bias received signals. 
 
 
     
     
       2. The receiver of  claim 1  wherein the disturbance rejection block comprises:
 a series of resistors configured to couple between the terminals of said receiving antenna; and 
 a common-mode voltage adjustor configured to adjust a voltage between an intermediate terminal of said resistors and a ground based on a reference voltage. 
 
     
     
       3. The receiver of  claim 2  wherein the common-mode voltage adjustor comprises:
 a transistor output stage configured to modify the voltage between the intermediate terminal of the resistors and the ground; and 
 a differential stage configured to receive said voltage between the intermediate terminal of said resistors and the ground and said reference voltage, and to drive the transistor output stage. 
 
     
     
       4. The receiver of  claim 2  wherein the common-mode voltage adjustor comprises:
 two transistor output stages configured to modify voltages at respective ends of the series of resistors; and 
 a differential stage configured to receive said voltage between the intermediate terminal of said resistors and the ground, and said reference voltage, and to drive the two transistor output stages. 
 
     
     
       5. The receiver of  claim 1 , further comprising:
 a wideband-voltage differential amplifier configured to amplify a received signal and having a cut-off frequency substantially equal to double a band-center frequency of a received signal, said amplifier comprising at least one capacitor configured to filter a direct current component of an output of the amplifier and keep it at a value to allow polarization downstream of the amplifier. 
 
     
     
       6. The receiver of  claim 1 , further comprising:
 an amplifier configured to amplify a received signal, said amplifier comprising a fast comparator fed back with an error amplifier adapted to reset an offset of the received signal, said error amplifier being configured to compare an output signal of the fast comparator with a reference signal and keep a direct current component of an output signal of the amplifier at a value to polarize the receiver downstream of the amplifier. 
 
     
     
       7. The receiver of  claim 1 , further comprising a transimpedance stage configured to coupled to terminals of the receiving antenna wherein:
 the common-mode disturbance rejection block comprises a clamp configured to take up parasite currents present on the terminals of the receiving antenna; and 
 the common-mode voltage biasing block comprises a common-mode voltage follower configured to bias the transimpedance stage in order to balance effects of the parasite currents present on the terminals of the receiving antenna. 
 
     
     
       8. The receiver of  claim 7  wherein the clamp comprises two circuit branches having a series of a PMOS transistor and an NMOS transistor coupled between a supply voltage and a ground and having a drain terminal in common, the PMOS transistors being driven by a reference voltage and gate and drain terminals of the NMOS transistors being configured to couple to the terminals of the receiving antenna. 
     
     
       9. The receiver of  claim 8  wherein said transimpedance stage comprises two MOS transistors having gate terminals in common and source terminals configured to couple to the terminals of the receiving antenna, and the common-mode voltage follower comprises two MOS transistors having gate and drain terminals in common and source terminals configured to couple to the terminals of the receiving antenna, the gate terminals of the transistors of the common-mode voltage follower and of the transistors of the transimpedance stage being coupled together to a polarization current generator. 
     
     
       10. The receiver of  claim 8  wherein said transimpedance stage comprises two MOS transistors having a gate terminal in common and source terminals configured to couple to the terminals of the receiving antenna, and said common-mode voltage follower comprises:
 a series of resistors configured to couple to the terminals of the receiving antenna; and 
 a series of first and second MOS transistors each having respective gate and drain terminals coupled together, wherein a source terminal of the first MOS transistor is coupled to a ground, the first MOS transistor has a gate terminal coupled to an intermediate terminal of said series of resistors and to the source terminal of the second transistor, and a drain terminal of the second MOS transistor being coupled to gate terminals of the transistors of the transimpedance stage and to a polarization current generator. 
 
     
     
       11. The receiver of  claim 1  wherein the receiver is a receiver of a transceiver, the transceiver including a transmitter and the galvanically isolated wireless interface. 
     
     
       12. A system, comprising:
 a transmitter; 
 a galvanically isolated wireless interface having a first antenna coupled to the transmitter and a second antenna; and 
 a receiver coupled to the second antenna of the galvanically isolated wireless interface and having a disturbance rejection block configured to compensate for parasitic currents flowing between the first and second antennas at potential variations between an input and an output of the galvanically isolated wireless interface, the disturbance rejection block comprising:
 a common-mode disturbance rejection block configured to take up parasitic currents present on the terminals of the second antenna; and 
 a common-mode voltage biasing block configured to bias received signals. 
 
 
     
     
       13. The system of  claim 12  wherein the disturbance rejection block comprises:
 a series of resistors configured to couple between the terminals of the second antenna; and 
 a common-mode voltage adjustor configured to adjust, based on a reference voltage, a voltage between an intermediate node of the series of resistors and a ground. 
 
     
     
       14. The system of  claim 13  wherein the common-mode voltage adjustor comprises:
 a transistor output stage configured to modify the voltage between the intermediate terminal of the resistors and the ground; and 
 a differential stage configured to receive the voltage between the intermediate terminal of the series of resistors and the ground, and the reference voltage, and to drive the transistor output stage. 
 
     
     
       15. The system of  claim 13  wherein the common-mode voltage adjustor comprises:
 two transistor output stages configured to modify voltages at respective ends of the series of resistors; and 
 a differential stage configured to receive the voltage between the intermediate terminal of the series of resistors and the ground, and the reference voltage, and to drive the two transistor output stages. 
 
     
     
       16. The system of  claim 13  wherein the receiver further comprises:
 a wideband-voltage differential amplifier configured to amplify a received signal and having a cut-off frequency substantially equal to double a band-center frequency of a received signal, the amplifier comprising at least one capacitor configured to filter a direct current component of an output of the amplifier and keep it at a value to allow polarization downstream of the amplifier. 
 
     
     
       17. The system of  claim 12  wherein the receiver further comprises:
 an amplifier configured to amplify a received signal, the amplifier comprising a fast comparator fed back with an error amplifier adapted to reset an offset of the received signal, the error amplifier being configured to compare an output signal of the fast comparator with a reference signal and keep a direct current component of an output signal of the amplifier at a value to polarize the receiver downstream of the amplifier. 
 
     
     
       18. The system of  claim 12  wherein the receiver further comprises a transimpedance stage coupled to terminals of the second antenna and wherein:
 the common-mode disturbance rejection block comprises a clamp configured to take up parasite currents present on the terminals of the second antenna; and 
 the common-mode voltage biasing block comprises a common-mode voltage follower configured to bias the transimpedance stage in order to balance effects of the parasite currents present on the terminals of the second antenna. 
 
     
     
       19. The system of  claim 18  wherein the clamp comprises two circuit branches having a series of a PMOS transistor and an NMOS transistor coupled between a supply voltage and a ground and having a drain terminal in common, the PMOS transistors being driven by the reference voltage and the NMOS transistors having gate and drain terminals coupled to the terminals of the second antenna. 
     
     
       20. The system of  claim 19  wherein the transimpedance stage comprises two MOS transistors having gate terminals in common and source terminals coupled to the terminals of the second antenna, and the common-mode voltage follower comprises two MOS transistors having gate and drain terminals in common and source terminals coupled to the terminals of the second antenna, the gate terminals of the transistors of the common-mode voltage follower and of the transistors of the transimpedance stage being coupled together to a polarization current generator. 
     
     
       21. The system of  claim 19  wherein the transimpedance stage comprises two MOS transistors having a gate terminal in common and source terminals coupled to the terminals of the second antenna, and the common-mode voltage follower comprises:
 a series of resistors coupled to the terminals of the second antenna; and 
 a series of first and second MOS transistors each having respective gate and drain terminals coupled together, wherein a source terminal of the first MOS transistor is coupled to a ground, the first MOS transistor has a gate terminal coupled to an intermediate terminal of said series of resistors and to the source terminal of the second transistor, and a drain terminal of the second MOS transistor being coupled to gate terminals of the transistors of the transimpedance stage and to a polarization current generator. 
 
     
     
       22. A receiver, comprising:
 means for amplifying signals received through a galvanically isolated wireless interface; and 
 means for compensating for parasitic currents flowing between a transmitting antenna and a receiving antenna at potential variations between an input and an output of the galvanically isolated wireless interface, the means for compensating including:
 means for taking up parasitic currents present on terminals of the receiving antenna; and 
 means for biasing the means for amplifying. 
 
 
     
     
       23. The receiver of  claim 22  wherein the means for compensating comprises:
 a series of resistors configured to couple between terminals of a receiving antenna of the wireless interface; and 
 means for adjusting a voltage between an intermediate terminal of said series of resistors and a ground based on a reference voltage. 
 
     
     
       24. The receiver of  claim 23  wherein the means for adjusting comprises:
 a transistor output stage configured to modify the voltage between the intermediate terminal of the series of resistors and the ground; and 
 a differential stage configured to receive said voltage between the intermediate terminal of said series of resistors and the ground and said reference voltage, and to drive the transistor output stage. 
 
     
     
       25. The receiver of  claim 23  wherein the means for adjusting comprises:
 means for modifying voltages at respective ends of the series of resistors; and 
 means for driving the means for modifying based on the voltage between the intermediate terminal of the resistors and the ground, and the reference voltage. 
 
     
     
       26. The receiver of  claim 22  wherein the means for amplifying comprises:
 a wideband-voltage differential amplifier configured to amplify a received signal and having a cut-off frequency substantially equal to double a band-center frequency of a received signal, said amplifier having means for filtering a direct current component of an output of the amplifier and maintaining polarization. 
 
     
     
       27. The receiver of  claim 22  wherein the means for amplifying comprises means for maintaining polarization of received signals. 
     
     
       28. The receiver of  claim 27  wherein the means for maintaining polarization comprises a fast comparator fed back with an error amplifier adapted to reset an offset of a received signal, said error amplifier being configured to compare an output signal of the fast comparator with a further reference signal and keep a direct current component of an output signal of the amplifier at a value to polarize the receiver downstream of the amplifier. 
     
     
       29. The receiver of  claim 22 , comprising means for converting a current signal to a voltage signal, wherein:
 the means for taking up parasitic currents comprises means for clamping the terminals of the antenna; and 
 the means for biasing comprises means for modifying a polarization of the means for amplifying. 
 
     
     
       30. The receiver of  claim 22 , further comprising means for decoding received signals. 
     
     
       31. A method, comprising:
 receiving a signal through a galvanically isolated wireless interface having first and second antennas; 
 rejecting common-mode transients of the received signal at potential variations between an input and an output of the galvanically isolated wireless interface by:
 taking up parasitic currents present on terminals of the second antenna; 
 biasing the received signal; and 
 
 amplifying the received biased signal. 
 
     
     
       32. The method of  claim 31 , further comprising decoding the amplified signal. 
     
     
       33. The method of  claim 31  wherein the biasing comprises:
 adjusting, based on a reference voltage, a voltage at an intermediate node of a series of resistors coupled between terminals of the second antenna of the wireless interface. 
 
     
     
       34. The method of  claim 33  wherein the adjusting comprises:
 modifying voltages at respective ends of the series of resistors. 
 
     
     
       35. The method of  claim 31  wherein the amplifying comprises:
 filtering a direct current of the amplified signal while maintaining polarization. 
 
     
     
       36. A receiver, comprising:
 a disturbance rejection block configured to receive signals from a receiving antenna of a galvanically isolated wireless interface and to compensate for parasitic currents flowing between a transmitting antenna and the receiving antenna at potential variations between an input and an output of the galvanically isolated wireless interface, wherein the disturbance rejection block includes:
 a series of resistors configured to couple between terminals of the receiving antenna; 
 a transistor output stage configured to modify a voltage between an intermediate terminal of the resistors and a ground; and 
 a differential stage configured to receive the voltage between the intermediate terminal of the resistors and the ground and a reference voltage, and to drive the transistor output stage. 
 
 
     
     
       37. The receiver of  claim 36 , further comprising:
 a wideband-voltage differential amplifier configured to amplify a received signal and having a cut-off frequency substantially equal to double a band-center frequency of a received signal, said amplifier comprising at least one capacitor configured to filter a direct current component of an output of the amplifier and keep it at a value to allow polarization downstream of the amplifier. 
 
     
     
       38. A receiver, comprising:
 a disturbance rejection block configured to receive signals from a receiving antenna of a galvanically isolated wireless interface and to compensate for parasitic currents flowing between a transmitting antenna and the receiving antenna at potential variations between an input and an output of the galvanically isolated wireless interface, wherein the disturbance rejection block includes:
 a series of resistors configured to couple between terminals of the receiving antenna; 
 two transistor output stages configured to modify voltages at respective ends of the series of resistors; and 
 a differential stage configured to receive a voltage between an intermediate terminal of said resistors and a ground, and said reference voltage, and to drive the two transistor output stages. 
 
 
     
     
       39. The receiver of  claim 38  wherein the disturbance rejection block further comprises a clamp configured to take up parasitic currents present on the terminals of the receiving antenna.